IS 1367( Part 3 ) :2002 ISO 898-1:1999 (dk-n p%m) Indian Standard TECHNICAL SUPPLY CONDITIONS FOR THREADED STEEL FASTENERS PART 3 MECHANICAL PROPERTIES OF FASTENERS MADE OF CARBON STEEL AND ALLOY STEEL -- BOLTS, SCREWS AND STUDS ( Fourth Revision) ICS21.O6O.1O @ BIS 2002 BUREAU MANAK OF INDIAN 9 BAHADUR STANDARDS SHAH ZAFAR MARG BHAVAN, NEW DELHI 110002 December 2002 Price Group 10 IS 1367( Part 3 ) :2002 ISO 898-1:1999 Bolts, Nuts and Fasteners Accessories Sectional Committee, BP 33 NATIONAL FOREWORD This Indian Standard ( Fourth Revision) which is identical with ISO 898-1:1999 `Mechanical properties of fasteners made of carbon steel and alloy steel -- Part 1 : Bolts, screws and studs' issued by the International Organization for Standardization ( ISO ) was adopted by the Bureau of Indian Standards on the recommendations of the Bolts, Nuts and Fasteners Accessories Sectional Committee and approval of the Basic and Production Engineering Division Council. IS 1367 which covers the `Technical supply conditions for threaded steel fasteners' was originally published in 1961 and first revised in 1967. In the late seventies, the second revision was taken up when the work of lSOflC 2, `Fasteners' taken into consideration of our national work on industrial fasteners. Accordingly, the Committee decided that IS 1367 should be brought out into several parts, each part covering a particular feature or property of the fasteners. Subsequently, the second revision of this standard was published in 1979. The third revision was published in 1991 by adoption of ISO 898-1 :1988. This fourth revision has been prepared by adoption of latest edition of ISO 898-1 published in 1999. The text of ISO Standard has been approved as suitable for publication as Indian Standard without deviation. Certain terminology and conventions are, however, not identical to those used in the Indian Standards. Attention is drawn especially to the following: a) Wherever the words `International read as `Indian Standard'. Standard' appear referring to this standard, they should be b) Comma ( , ) has been used as a decimal marker while in Indian Standards, is to use a point ( . ) as the decimal marker. the current practice In this adopted standard, reference appears to certain International Standards for which Indian Standards also exist. The corresponding Indian Standards which are to be substituted in their place are listed below along with their degree of equivalence for the editions indicated: International Standard ISO 68-1:1998 Corresponding Indian Standard Degree of Equivalence Identical IS 4218 ( Part 1 ) :1999 ISO General purpose metric screw thread: Part 1 Basic profile ( second revision) IS 1499:1977 Method for Charpy impact test ( U-notch ) for metals ( first revision) IS' 4218 ( Part 2 ) :2001 ISO General purpose metric screw threads: Part 2 General Plan ( second revision) IS 4218 ( Part 4 ) :2001 ISO General purpose metric screw threads: Part 4 Selected sizes for screws, bolts and nuts ( second revision) IS 4218( Part 3 ): 1999 ISO General purpose metric screw threads: Part 3 Basic dimensions ( second revision) IS 1367 ( Part 6 ) :1994 Technical supply conditions for threaded steel fasteners: Part 6 Mechanical properties and test methods for nuts with specified proof loads ( third revision) (i) ISO 83:1976 Technically equivalent Identical ISO 261:1998 ISO 262:1998 do ISO 724: 19781) do ISO 898-2:1992 do 1) since ~~visedin 1993. IS 1367( Part 3 ): 2002 ISO 898:1:1999 International Standard ISO 898-5:1998 Corresponding Indian Standard Degree of Equivalence Identical IS 1367 ( Part 5 ) :2002 Technical supply conditions for threaded steel fasteners: Part ~ Mechanical properties and test methods for set scre~s and similar threaded fasteners not under tensile stresses ( third rhision ) IS 1367 ( Part 20 ) : 1996 Industrial fasteners -- Threaded steel fasteners -- Technical supply conditions -- Mechanical properties: Part 20 Torsional test and minimum torques for bolts and screws with nominal diameters 1 mm to 10 mm IS 14962 ( Part 1 ) :2001 ISO General purpose metric screw threads -- Tolerances: Part 1 Principles and basic data IS 14962 ( Part 2 ) :2001 ISO General purpose metric screw threads -- Tolerances: Part 2 Limits of sizes for general purpose external and internal screw threads -- Medium quality IS 1367 ( Part 17 ) : 19962) Industrial fasteners -- Threaded steel fasteners -- Technical supply conditions: Part 17 Inspection, sampling and acceptance procedure ( third revision). IS 1367 ( Part 11 ) :2002 Technical supply conditions for threaded steel fasteners: Part 11 Electroplated coatings ( third revision) IS 1367 ( Part 2 ) :2002 Technical supply conditions for threaded steel fasteners: Part 2 Product grades and tolerances ( third revision) IS 1367 ( Part 9/See 1 ) : 1993 Technical supply conditions for threaded steel fasteners : Part 9 Surface discontinuities; Section 1 Bolts, screws and studs for general applications ( third revision) IS 1367 ( Part 10 ): 2002 Technical supply conditions for threaded steel fasteners : Part 10 Surface -- Nuts ( third revision) discontinuities IS 1367 ( Part 9/See 2 ) : 1993 Technical supply conditions for threade39 mm), provided that all mechanical requirements of the property classes are met. 1 IS ISO 1367 898-1 (Part 3):2002 :1999 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of ISO 898. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of ISO 898 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 68-1:1998, ISO 83:1976, ISO 261:1998, ISO 262:1998, ISO 273:1979, ISO 724:1978, ISO general purpose screw threads ­ Basic profile ­ Part 1: Metric scre w threads, Steel ­ Charpy impact test (U-notch), /S0 genera/ purpose metric screw threads ­ Genera/plan. ISO general purpose metric screw threads ­ Selected sizes for screws, bolts and nuts. Fasteners - Clearance holes for bolts and screws. ISO general purpose metric screw threads ­ Basic dimensions. made of carbon steel and alloy steel ­ Part 2: Nuts with ISO 898-2:1992, Mechanical properties of fasteners specified proof load values ­ Coarse thread. ISO 898-5:1998, Mechanical properties of fasteners made of carbon steel and alloy steel ­ Part 5: Set screws and similar threaded fasteners not under tensile stresses. ISO 898-7:1992, Mechanical propetiies of fasteners made of carbon steel and alloy steel ­ Part 7: Torsional and minimum torques for bo/ts and screws with nomina/ diameters 1 mm to 10 mm. ISO 965-1:1998, ISO general purpose metric screw threads ­ Tolerances ­ Part 1: Principles and basic data. Tolerances ­ Part 2: Limits of sizes for general test ISO 965-2:1998, ISO general purpose metric screw threads purpose external and internal screw threads ­ Medium quality. ISO 6157-1:1988, ISO 6157-3:1988, ISO 6506:1981, ISO 6507-1:1997, ISO 6508:1986, ISO 6892:1998, Fasteners ­ Surface discontinuities Fasteners ­ Surface discontinuities ­ Part 1: Bolts, screws and studs for general requirements. ­ Part 3: Bolts, screws and studs for special requirements. Mets//ic materia/s ­ Hardness test - Brine// test. Mets//ic materia/ - Hardness test ­ Vickers test ­ Part 1: Test method. Mets//ic materia/s - Hardness test - Rockwell test (sea/es A - B - C - D - E - F - G - H - K). Metallic materials - Tensile testing at ambient temperature. 3 Designation system The designation system for property classes of bolts, screws and studs is shown in table 1. The abscissae show the nominal tensile strength values, R~, in newtons per square millimetre, while the ordinates show those of the minimum elongation after fracture, Amin, as a percentage. The property class symbol consists of two figures: -- the first figure indicates table 3); 1/1 00 of the nominal tensile strength in newtons per square millimetre (see 5.1 in -- the second figure indicates 10 times the ratio between lower yield stress ReL (or stress proportional elongation RPO,J and nominal tensile strength Rm, nom (yield stress ratio), at 0,2 `Io non- 2 IS ISO 1367 898-1 (Part 3) :2002 :1999 The multiplication of these two figures will give 1/1 O of the yield stress in newtons per square millimetre. RP0,2,~in) and The minimum lower yield stress ReL ~in, (or minimum stress at 0,27. non-proportional elongation minimum tensile strength Rm, ~in,are equal to or greater than the nominal values (see table 3). 4 Materials Table 2 specifies steels and tempering temperatures The chemical composition for the different property classes of bolts, screws and studs with the relevant ISO standards. shall be assessed in accordance 5 Mechanical and physical properties When tested by the methods described in clause 8, the bolts, screws and studs shall, at ambient temperature, have the mechanical and physical properties set out in table 3. -3 IS ISO 1367 898-1 (Part 3) :2002 :1999 Table 1 -- System Nominal tensile strength Rm, nom N/mm2 7 8 300 400 500 of coordinates 600 700 800 900 1000 1200 1400 6.8 9 10.9 10 5.8 12 8.8 14 Mlinimum elongation after fracture, Aminpercent 4.8 16 18 20 5.6 22 4.6 25 3.6 30 g,8a 12.9 Relationship between yield stress and tensile strength .6 60 X1OO% .8 80 .9 90 Second figure of symbol Lower yield stress ReLb Nominal tensile strength jr Stress at0,2%non-proportional Nominal tensile strength elongation Rm,nom Rpo,2bx100Y, Rm,nom NOTE Although a great number of property classes are specified in this part of ISO 898, this does not mean that all classes are appropriate for all items. Further guidance for application of the specific property classes is given in the relevant product standards. For non-standard items, it is advisable to follow as closely as possible the choice already made for similar standard items. a b Applies only to thread diameter d < 16 mm. Nominal values according to table 3 apply. 1S 1367 ISO Table 2 -- Steels Property class Material and treatment Chemical composition limits 898-1 (Part 3) :2002 :1999 (check analysis) % (drrr) c min. max. 0,20 0,55 P max. 0,05 0,05 s max. 0,06 0,06 Ba max. 0,003 0,003 Tempering temperature `c min. ­ ­ 3.6 b 4m6b 4.8 b 5.6 5.8 b 6.8 b 8.4 c Carbon steel 0,13 -- 0,55 0,55 0,05 0,05 0,06 0,06 0,003 Carbon steel with additives (e.g. B, Mn or Cr) quenched and tempered Carbon steel quenched and tempered o,15d 0,25 o,15d 0,25 o,15d 0,25 0720 d 0,20 0,28 0,40 0,55 0,35 0,55 0,35 0,55 0955 0,55 0,50 0,035 0,035 0,035 0,035 0,035 0,035 0,035 0,035 0,035 0,035 0,035 0,035 0,035 0,035 0,003 425 9.8 Carbon steel with additives (e.g. B, Mn or Cr) quenched and tempered Carbon steel quenched and tempered 0,003 425 llJ$Je f 10.9f Carbon steel with additives (e.g. B, Mn or Cr) quenched and tempered Carbon steel quenched and tempered Carbon steel with additives (e.g. B, Mn or Cr) quenched and tempered Alloy steel quenched and tempered 9 0,003 0,003 340 425 0,03 5 0,035 0,03 5 0,03 5 0,00 3 380 Isogf hi Alloy steel quenched 0/0 and tempered 9 a Boron content can reach 0,005 provided that non-effective boron is controlled by addition of titanium and/or aluminium. b Free cutting steel is allowed for these property classes with the following maximum sulfur, phosphorus and lead contents: sulfur 0,34 O/O; phosphorus 0,11 Y.; lead 0,35 O/.. For nominal diameters above 20 mm the steels specified for property classe 10.9 may be necessary in order to achieve c sufficient hardenability. d In case of plain carbon boron steel with a carbon content below 0,25 content shall be 0,6 Y. for property class 8.8 and 0,7 `ZO for 9.8, 10.9 and ~. Y. (ladle analysis), the minimum manganese e Products shall be additionally identified by underlining the symbol of the property class (see clause 9). All properties of 10.9 as specified in table 3 shall be met by ~, however, its lower tempering temperature gives it different stress relaxation characteristics at elevated temperatures (see annex A). f For the materials of these property classes, it is intended that there should be a sufficient hardenability to ensure a structure consisting of approximately 90 0/0 martensite in the core of the threaded sections for the fasteners in the "as-hardened condition before tempering. g This alloy steel shall contain at least one of the following elements in the minimum quantity given chromium 0,30 Y., nicke: 0,30 %, molybdenum 0,20%, vanadium 0,10 % Where elements are specified in combinations of two, three or four and have alloy contents less than those given above, the limit value to be applied for class determination is 70 ?4. of the sum of the individual limit values shown above for the two, three or four elements concerned. h A metallographically detectable white phosphorous enriched layer is not permitted for property class 12.9 on surfaces subjected to tensile stress. i The chemical composition and tempering temperature are under investigation. 5 IS ISO 1367 898-1 (Part 3):2002 :1999 Table 3 -- Mechanical and physical properties of bolts, screws and studs Proparfy class 8.8' J< 16C mm 16C mm 600 830 255 335 242 316 . 23 -- 34 9 900 900 290 360 276 342 -- 28 -- 37 1000 1040 320 360 304 361 -- 32 _ 39 1200 1220 365 435 366 414 . 39 _ 44 9.8b 10.9 12.9 Sub-clause number Mechanical and physical property 3.6 4.6 4.8 5.6 5.8 6.8 51 5.2 53 Nommal tensde strength, Rm, nom Minimum tensile strength, Rm,~,nd e V,ckers hardness, HV F298N Nlmm2 N/mmz min. max. min. max. 300 330 95 400 120 400 420 130 220' 500 500 520 160 600 600 190 250 800 800 250 320 236 304 -- 155 54 Brinell hardness, HB F=30D2 min. 90 114 124 209' I 147 152 161 236 HRB HRC 52 -- 67 -------- 71 I 79 62 69 - 5.5 Rockwell hardness. HR max. 22 -- 32 HRE HRC 95,0' -- -- 160 240 240 320 340 -- -- 3CS3 3(XJ 400 420 66,5 -- 56 57 Surface hardneas, HV 0,3 Lower yield stress R&h, Nlmm2 max. nom, mm. nom. min. 0,94 160 0,94 225 4.90 480 -- -- -- 640 640 -- -- -- -- -- --' -- -- 1080 1 100 0,66 970 1s0 5.6 Stress at 0,2% rmn.proportional 640 660 0,91 600 720 720 0,90 650 See ISO 698-7 900 940 0,66 630 elongation RW,2', N/mmz 5.9 Stress under proof load, Sp 5.10 5.11 5.12 513 5.14 5.15 5.16 Breaking torque, MB S$R,L Or 5dRW,2 N/mm2 Nm min. min. % min. 0,91 310 0,93 260 -- 0,90 360 0,92 440 0,91 560 Percent elongation after fracture, A Reductmn area after fracture, Z Strength under wedge Ioadmg e Impact strength, KU Head soundness Minimum height of "on-decarburized thread zone, E 25 1 22 -- I -- 20 -- I 12 I 52 12 I 10 46 I 9 46 8 44 The values for full size bolts and screws (no studs) shall not be smaller than the minimum values for tensile strength shown in 5.2 J min. -- I 25 -- I I No fracture -- L HI 2 ~ /{1 3 0,015 Reductmn of hardness 20 HV maximum ~ !{l 4 30 I 30 I 25 20 1 15 Maximum depth of complete decarburlzatlon, G 5.17 5.16 a Hardness after retempering Surface intagrity mm -- -- I In accordance with ISO 6157-1 or ISO 6157-3 as aomoDriate ,., in dian'alerad s 16 mm, there is an increaati @of load, Referenceto ISO 898.2 is racommendad. For bolts of proparty class B,8 nti stfipp+ng in the me of i"advetient over-tightening indutinga load m excess of proof b c d Appfiasenly to nominalthreaddiarnsfers d =s16 mm. For structuralMing the fimitis 12 mm appfieato prodma of fength/ <2,5 d and otherproductswhichcannotbe tensAe- Minimumte173ile propertiesappiyto prcducfaof nominallength/ a 2,5 d, Minimumhard~~ teafsd (e.g. due to haad camfiguration). e I 9 When leafingfull-sizeboffs,screwsand studs,the tensileIMCIS,whiti are to be eppfiadforthe calcufafion of Rm, shall meet the values givenin tablea6 and B. A hardneaareadingtsken at the end of kits, acrewaand studsshallbs 25o HV, 2W HB or 9S,5 HRB mtimum. rneaaurd COrShadn~ cmth pfodd tien readin~ of bth suffa@ and mre are csrriad oui at HV 0,3. $h'faCs hardnaa.s ahalf fS3t be more than 30 Vidiem @nks Sbevelh For proparty daaa 10.9, any increaaa in harctaeas at ths aurfaca Wish h In cases whara the lower yield stress Rti cannot be determined, and 6.8 the values for RA are givan indicates thatthe surface hardness ex@ada 3s0 HV is not acceptable. to meaaura the afresa at 0,2% ncmprefxxticmal elongation RN p. FOr the PrOPe~Y classea if ia penniaaifje 4.8,5.8 fer calculationpurposesonly, they are nottest valuea. I Tha yield afraaa ratio accordingto the deaignaficm of the propartydaaa and the minimumafrsaaat 0,2 % non-propfionai elongationR@,2 W@y fo machinad test sP*lmens. if raceivadfromtaafaof fullsize M@ and asrawaW vaty kaea of pmcaa.si~ methodand skis effacta. Th6Se vafues 6 1S 1367 ISO 898-1 (Part 3) :2002 :1999 6 Mechanical and physical properties to be determined Two test programmed, A and B, for mechanical and physical properties of bolts, screws and studs, using the methods described in clause 8, are set out in table 5. Regardless of the choice of test programme, all requirements of table 3 shall be met. The application of programme B is always desirable, but is mandatory than 500 kN if the application of programme A is not explicitly agreed. Programme for products with ultimate tensile loads less A is suitable for machined test pieces and for bolts with a shank area less than the stress area. Table 4 -- Key to test programmed Size (see table 5) Bolts and screws with thread diameter d>3mm I and length 1 ==2,54 c Bolts and screws with thread diameter d<3mm I Test decisive for acceptance I a or length 1 <2,5 @ I I o I I Also bolts and screws with special head or shank configurations which are weaker than the threaded section. IS ISO 1367 898-1 (Part 3) :2002 : 1999 Table 5 -- Test programmed \l A and B for acceptance Lal purposes n.,...aA;a_\ ~lU~C$lLIC>) ll_h-.-- plu~cuulca -.-,.fi~i,.-.Ilcac apply -nml., +,. -mnha_;_at GLllalll Lw Ill UUL k,, + ,.,. IIUL + _h.-. Ul!cllllu.al -nl-nl Property Test Iroup Test programme A Test method Property class 3.6,4.6 5.6 8.8,9.8 10.9 12.9 Test programme B Test method Property class 3.6,4,6 4.8, 5.6 5.8, 6.8 8.2 Tensile test a 8,8,9.8 10.9 12.9 I 5.2 Minimum tensile strength, R m, mm. 8.1 Tensile test q q q q 5.3 and 5.4 and 5.5 Minimum hardness b 8.4 Hardness test c o 0 8.4 Hardness test c o 0 Maximum hardness q q c q o 5.6 Maximum surface hardness 0 q 0 0 q o II 5.7 Minimum lower yield stress d `eL,.min. Stress at 0,2 % nonproportional el~gation, RDO ~ 0' 8.1 Tensile test q q 5.8 8.1 Tensile test 5.9 Stress under proof load, SP 8.5 Proof load test q q o 5.10 Ill 5.11 Breaking torque, hlB Minimum percent elongation after fracture, Amin d 8.1 Tensile test 8.3 Torsional test e q q 5.12 Minimum reduction of area af@r fracture Zmin Strength under wedge loading f 8.1 Tensile test q 8.6 Wedge loading test a 5,13 q q Iv 5,14 5.15 Minimum impact strength, K U Head soundness' Maximum dacarburized zone Hardness after [tempering Surface integrity 8.7 Impact test g qh q 8.8 Head soundness test Decarbunzation test Retempering test J o 0 q o v 5.16 8.9 Decarburization test Retempering test i q o 8,9 5.17 8.10 q o 8.10 q 0 5.18 8.11 Surface discontinuity inspection q q 8.11 o 0 Surface discontinuity inspection q q o 0 I o If the wedge loading testis satisfactory, the axialtensiletestis notrequired. Minimumhardness appliesonly to prcducts of nominal length I <2,5 J and other produds which cannot be tensile tested or torsional tested (e.g. due to head configuration). c d e f 9 h I j Hardnessmaybe Vickers,Brinell or Rockwell. Incaseofdoubt, theVickerehardness testis decisive for acceptance. Only for bolts or screws with length{= W, Only if IAts or screws cannot be tensile tested. Special head bolts and screws with configurationswhich are weaker than the threaded section are excluded from wedge tensile testing requirements. Only for bolts, screws and studs with thread diameters d >16 mm and only if required by the purchaser. Only properly class 5.6. Only for belts and screws with thread diameters ds 10 mm and lengths too shortto permit wedge bad testing Test not mandatory, to be applied as a referee test in the case of dispute only. 8 IS ISO 1367 898-1 (Part 3) :2002 :1999 7 Minimum ultimate tensile loads and proof loads See tables 6, 7, 8 and 9, Table 6 -- Minimum Nominal stress ultimate tensile loads ­ ISO metric coarse pitch thread "bread a Property class area ((i) Ab s, nom ~m2 3.6 4.6 4.8 5.6 5.8 6.8 8.8 9.8 q 10.9 12.9 Minimum ultimate tensile load (As, nom x Rm, Min),N M3 M3,5 M4 M5 M6 M7 M8 Ml O Ml 2 M14 M16 Ml 8 M20 5,03 6,78 8,78 14,2 20,1 28,9 36,6 58 84,3 115 157 192 245 1660 2240 2900 4690 6630 9540 12100 19100 27800 38000 51800 63400 80800 2010 2710 3510 5680 8040 11600 14600 23200 33700 46000 62800 76800 98000 2110 2850 3690 5960 8440 12100 15400 24400 35400 48300 65900 80600 103000 2510 3390 4390 7100 10000 14400 18300 29000 42200 57500 78500 96000 122000 2620 3530 4570 7380 10400 15000 19000 302@3 43800 59800 81600 99800 3020 4070 5270 8520 12100 17300 22000 34800 50600 69 ()()0 94000 115000 4020 5420 7020 11350 16100 23100 29200 46400 67400C 4530 6100 7900 12800 18100 26000 32900 52200 75900 5230 7050 9130 14800 20900 30100 38100 60300 87700 120000 163 ()()() 200000 6140 8270 10700 "17300 24500 35300 44600 70800 103000 140000 192000 234000 92 OOOC 104000 125 Oooc 141 ()()() 159 Crr)o -- 127 ()()() 147000 203000 252000 293000" 381000 466000 576000 678000 810000 WSO -- -- -- -- -- -- -- -- 255000 315000 367000 477000 583000 722000 850000 1020000 299000 370000 431000 560000 684000 847000 997000 1200000 M22 M24 M27 M30 M33 M36 M39 a b c 303 353 459 561 694 817 976 100000 116000 152000 121000 141000 184000 127000 148000 193000 236000 292000 343000 410000 152000" 158000 176 ()()o 184000 230000 280000 347000 408000 488000 239000 292000 361000 425000 508000 182 (joo 212000" 275000 337000 416000 49(3000 586000 185000 224000 229000 270000 322000 278000 327000 390000 Whereno threadpitchis indicatedin a To calculate thread designation, coarse pitch is specified. This is given 261 and ISO 262. As see 8.2. N, 95500 N and 130000 N, For structural bolting 70000 respectively. 9 IS ISO 1367 898-1 (Part 3) :2002 :1999 Table 7 -- Proof loads ­ ISO metric rhread a ((/) Nominal stress area ~b s, nom coarse pitch thread Property class mm2 3.6 4.6 4.8 5.6 5.8 6.8 8.8 9.8 10.9 12.9 Proof load (As nOm x SP), N M3 M3,5 M4 M5 5,03 6,78 8,78 14,2 910 1220 1580 2560 1 130 1530 1980 3200 1560 2100 2720 1410 1900 2460 1910 2580 3340 2210 2980 3860 2920 3940 5100 3270 4410 5710 4180 5630 7290 4880 6580 8520 4400 6230 8960 11400 18000 26100 35600 48700 59500 76000 93900 109000 142000 174000 215000 253000 303000 3980 5630 8090 10200 16200 23600 32200 44000 53800 68600 84800 98800 128000 157000 194000 229000 273000 5400 7640 11000 13900 22000 32000 43700 59700 73000 93100 115000 134000 174000 213000 264000 310000 371000 6250 8840 12700 16100 25500 37100 50600 69100 84500 108000 133000 155000 202000 247000 305000 359000 429000 8230 11600 16800 21200 33700 48900 c 66700 c 91000 c 115000 147000 182000 212000 275000 337000 416000 490000 586000 9230 13100 18800 23800 37700 54800 74800 102000 -- -- -- -- -- -- -- -- -- 11800 16700 24000 30400 48100 70000 95500 130000 159000 203000 252000 293000 381000 466000 576000 678000 810000 13800 19500 28000 .35500 56300 81800 112000 152000 186000 238000 294000 342000 445000 544000 673000 792000 947000 M6 M7 M8 M1O M12 M14 M16 M18 M20 M22 M24 M27 M30 M33 M36 M39 a b c 20,1 28,9 36,6 58 84,3 115 157 192 245 303 353 459 561 694 817 976 3620 5200 6590 10400 15200 20700 28300 34600 44100 54500 63500 82600 101000 125000 147000 176000 4520 6500 8240 13000 19000 25900 35300 43200 55100 68200 79400 103000 126000 156000 184000 220000 Whereno threadpitchis indicatedin a threaddesignation, coarsepitchis specified. Thisis givenin ISO 261 and ISO 262, TO calculate As see 8.2. For structural bolting 50700 N, 68800 N and 94500 N, respectively. 10 IS ISO 1367 (Part 3) :2002 t999 898-1: Table 8 -- Minimum ultimate tensile loads - ISO metric fine pitch thread Thread Nominal stress ((/x Pa) area As, nom ~m2 Property class b 3.6 4.6 4.8 5.6 5.8 6.8 8.8 9.8 I 10.9 12.9 ------ 47800 78700 74700 112400 107500 152000 204000 264000 332000 406000 Minimum ultimate tensile load (As nom x Rm, ~in), N M8X1 M1OX1 M1OX1,25 M12x1,25 M12x1,5 M14x1,5 M16x1,5 M18x1,5 M20x1,5 M22x1,5 M24x2 39,2 64,5 61,2 92,1 88,1 125 167 216 272 333 384 12900 21300 20200 30400 29100 41200 55100 71300 89800 110000 127000 15700 25800 24500 36800 35200 50000 66800 86400 109000 133000 154000 16500 27100 25700 38700 37000 52500 70100 90700 114000 140000 161000 19600 32300 30600 46100 44100 62500 83500 108000 136000 166000 192000 20400 33500 31800 47900 45800 65000 86800 112000 141000 173000 200000 23500 38700 367oo 55300 52900 75000 100000 130000 163000 200000 230000 31360 51600 49000 73700 70500 100000 134000 179000 226000 276000 319000 35300 58100 55100 82900 79300 112000 150000 -- -- -- -- 40800 67100 63600 95800 91600 130000 174000 225000 283000 346000 399000 469000 605000 758000 928000 1055000 1260000 M27x2 M30x2 M33x2 M36x3 M39x3 496 621 761 865 1030 164000 205000 251000 285000 340000 198000 248000 304000 346000 412000 208000 261000 320000 363000 433000 248000 310000 380000 432000 515000 258000 323000 396000 450000 536000 298000 373000 457000 519000 618000 412000 515000 632000 718000 855000 -- -- -- -- -- 516000 646000 791000 900000 1070000 a p is the pitch of the threacf. b To calculate,4~see 8.2. 11 IS ISO 1367 898-1 (Part 3) :2002 :1999 Table 9 -- Proof loads - ISO metric fine pitch thread Thread ((/ x Pa) Nominal stress area As, nom b Mmz 3.6 4.6 4.8 5.6 5.8 6.8 8.8 9.8 10.9 12.9 Property class Proof load (As nom x $), N M8X1 Mloxl 39,2 64,5 7060 11600 8820 14500 12200 11000 14900 17200 22700 25500 32500 38000 20000 19000 28600 27300 38800 51800 67000 84300 103000 119000 154000 192000 236000 268000 319000 18100 17100 25800 24700 35000 46800 60500 76200 93200 108000 139000 174000 213000 242000 288000 24500 23300 35000 33500 47500 63500 82100 103000 126000 146000 188000 236000 289000 329000 391000 28400 26900 40500 38800 55000 73500 95000 120000 146000 169000 218000 273000 335000 381000 453000 37400 35500 53400 51 100 72500 96900 130000 163000 200000 230000 298000 373000 457000 519000 618000 41900 39800 59900 57300 81200 109000 -- -- -- -- -- -- -- -- -- 53500 50800 76400 73100 104000 139000 179000 226000 276000 319000 412000 515000 632000 718000 855000 62700 59400 89300 85500 121000 162000 210000 264000 323000 372000 481000 602000 738000 839000 999000 W1OX1,25 M12x1,25 M12x1,5 M14x1,5 M16x1,5 M18x1,5 M20x1,5 M22x1,5 M24x2 M27x2 M30x2 M33x2 M36x3 M39x3 a b 61,2 92,1 88,1 125 167 216 272 333 384 496 621 761 865 1030 11000 16600 15900 22500 30100 38900 49000 59900 69100 89300 112000 137000 156000 185000 13800 20700 19800 28100 37600 48600 61200 74900 86400 112000 140000 171000 195000 232000 P is th e pitch of the thread. TO calculate As see 8.2. 8 8.1 Test methods Tensile test for machined test pieces with ISO 6892. The following properties shall be checked on machined test pieces by tensile tests in accordance a) b) c) tensile strength, f?m; lower yield stress, ReL or stress at 0,2 percentage ~ = elongation after fracture: ~looyo ?4. non-proportional elongation, RP0,2; L'IJ-LO Lo d) percentage ~_ _-- so­s" reduction of area after fracture: ~ ,007, so 12 IS ISO 1367 898-1 (Part 3) :2002 :1999 The machined test piece shown in figure 1 shall be used for the tensile test. If it is not possible to determine the elongation after fracture due to the length of the bolt, the reduction of area after fracture shall be measured providing that L.Ois at least 3 dO. When machining the test piece, the reduction of the shank diameter of the heat-treated bolts and screws with d > 16 mm shall not exceed 25 `h of the original diameter (about 44 YO of the initial cross-sectional area) of the test piece. Products in property (see 8.2), classes 4.8, 5.8 and 6.8 (cold work-hardened products) shall be tensile tested full-size 11Key d = nominal diameter dO= diameter of test piece (dO< minor diameter of thread) b = threaded length (b z d) LO= 5 dOor (5,65 & ): original gauge length `, -1 I f-c = length of straight portion (LO+ G(.J ~= total length of test piece (L.c+ 2r + b) f.u = final gauge length (see ISO 6892:1 998) .SO = cross-sectional Su = cross-sectional r = fillet radius (r area before tensile test area after fracture for determination of elongation LOz 3 dO:original gauge length for determination of reduction of area Figure 1 -- Machined >4 mm) test piece for tensile testing 8.2 Tensile test for full-size bolts, screws and studs The tensile test shall be carried out on full-size bolts in conformity with the tensile test on machined test pieces (see 8.1 ). It is carried out for the purpose of determining the tensile strength. The calculation of the tensile strength, Rm, k based on the nominal stress area As nom: As, nom = ~ () [12 + (13 -- 2 2 where d2 d3 is the basic pitch diameter of the thread (see ISO 724); is the minor diameter of the thread in which d, H is the basic minor diameter (see ISO 724); is the height of the fundamental triangle of the thread (see ISO 68-l). For testing of full-size bolts, screws and studs the loads given in tables 6 to 9 shall be applied. 13 IS ISO 1367 898-1 (Part 3) :2002 :1999 When carrying out the test, a minimum free threaded length equal to one diameter (Id) shall be subjected to the tensile load. In order to meet the requirements of this test, the fracture shall occur in the shank or the free threaded length of the bolt and not at the junction of the head and the shank. The speed of testing, as detemined with a free-running cross-head, shall not exceed 25 mm/min. The grips of the testing machine should be self-aligning to avoid side thrust on the test piece. 8.3 Torsional test For the torsional test see ISO 898-7. The test applies to bolts and screws with nominal thread diameters ds 3 mm as well as to short bolts and screws with nominal thread diameters 3 mm < ds 10 mm which cannot be subjected to a tensile test. 8.4 Hardness test For routine inspection, hardness of bolts, screws and studs may be determined on the head, end or shank after removal of any plating or other coating and after suitable preparation of the test piece. For all property classes, if the maximum hardness is exceeded, a retest shall be conducted at the mid-radius position, one diameter back from the end, at which position the maximum hardness specified shall not be exceeded. In case of doubt, the Vickers hardness test is decisive for acceptance. Hardness readings for the surface hardness shall be taken on the ends or hexagon flats, which shall be prepared by minimal grinding or polishing to ensure reproducible readings and maintain the original properties of the surface layer of the material. The Vickers test HV 0,3 shall be the referee test for surface hardness testing. Surface hardness readings taken at HV 0,3 shall be compared with a similar core hardness reading at HV 0,3 in order to make a realistic comparison and determine the relative increase which is permissible up to 30 Vickers points. An increase of more than 30 Vickers points indicates carburization. For property classes 8.8 to 12.9 the difference between core hardness and surface judgeing of the carburization condition in the surface layer of the bolts, screws or studs. hardness is decisive for There may not be a direct relationship between hardness and theoretical tensile strength. Maximum hardness values have been selected for reasons other than theoretical maximum strength consideration (e.g. to avoid embrktlement). Careful differentiation should be made between an increase in hardness caused by carburization and that due to NOTE heat-treatment or cold working of the surface. 8.4.1 Vickers hardness test with ISO 6507-1. The Vickers hardness test shall be carried out in accordance 8.4.2 Brineil hardness test The Brinell hardness test shall be carried out in accordance 8.4.3 Rockwell hardness test with ISO 6506. The Rockwell hardness test shall be carried out in accordance 8.5 Proof with ISO 6508. load test for full-size bolts and screws The proof load test consists of two main operations, as follows: a) b) application of a specified tensile proof load (see figure 2); of permanent extension, if any, caused by the proof load. measurement 14 IS ISO 1367 898-1 (Part 3) :2002 : 1999 The proof load, as given in tables 7 and 9, shall be applied axially to the bolt in a tensile testing machine. The full proof load shall be held for 15 s. The length of free thread subjected to the load shall be one diameter (1J). For screws threaded to the head, the length of free thread subjected to the load shall be as close as practical to one diameter (Id). For measurement of permanent extension, the bolt or screw shall be suitably prepared at each end, see figure 2. Before and after the application of the proof load, the bolt or screw shall be placed in a bench-mounted measuring instrument fitted with spherical anvils. Gloves or tongs shall be used to minimize measurement error. To meet the requirements of the proof load test, the length of the bolt, screw or stud after loading shall be the same as before loading within a tolerance of i 12,5 Lm allowed for measurement error. The speed of testing, as determined with a free-running cross-head, shall not exceed 3 mm/min. The grips of the testing machine should be self-aligning to avoid side thrust on the test piece. Some variables, such as straightness and thread alignment (plus measurement error), may result in apparent elongation of the fasteners when the proof load is initially applied. In such cases, the fasteners may be retested using a 3 O/.greater load, and may be considered satisfactory if the length after this loading is the same as before this loading (within the 12,5 ~m tolerance for measurement error). Full-size screw x d 1---1 I Load Full-size bolt . Required "sphere to cone" contact between the measuring points and the centre-drilled holes in the end of the bolt or screw. a dh according to ISO 273, medium series (see table 10). Figure 2 -- Application of proof load to full-size bolts and screws 15 IS ISO 1367 898-1 (Part 3) :2002 :1999 ~ 8.6 Test for tensile strength under wedge loading of full-size bolts and screws (not studs) The wedge loading test shall not apply to countersunk head screws. described in ISO 6892 The test for strength under wedge loading shall be carried out in tensile testing equipment using a wedge as illustrated in figure 3. The minimum distance from the thread run-out of the bolt to the contact surface of the nut of the fastening device shall be d. A hardened wedge in accordance with tables 10 and 11 shall be placed under the head of the bolt or screw. A tensile test shall be continued until fracture occurs. To meet the requirements of this test, the fracture shall occur in the shank or the free threaded length of the bolt, and not between the head and the shank. The bolt or screw shall meet the requirements for minimum tensile strength, either during wedge tensile testing or in a supplementary tensile test without a wedge, according to the values given for the relevant property class before fracture occurs. Screws threaded to the head shall pass the requirement of this test if a fracture which causes failure originates the free length of thread, even if it has extended or spread into the fillet area or the head before separation. For product grade C, a radius r, should be used according to the formula r, = rmax + 0,2 in which rmax = da max ­ ds min 2 where r da ds is the radius of curvature under head; is the transition diameter; is the diameter of unthreaded shank. I_ (d/2)min. in I a dh according to ISO 273, medium series (see table 10). b c Hardness: 45 HRC min. Radius or chamfer of 45°. Figure 3 -- Wedge loading of full-size bolts 16 IS 1367 (Part 3) :2002 ISO 898-1 :1999 Table 10 -- Hole diameters for wedge loading tensile test Dimensions in millimetres Nominal thread diameter d 3 3,5 4 5 6 7 8 10 12 14 a dha 3,4 3,9 4,5 5,5 6,6 7,6 9 11 13,5 15,5 r, Nominal thread diameter d 16 18 20 22 24 27 30 33 36 39 dha 17,5 20 22 24 26 30 33 36 39 42 r, 0,7 0,7 0,7 0,7 0,7 0,8 0,8 0,8 0,8 1,3 1,3 1,3 1,3 1,6 1,6 1,6 1,6 1,6 1,6 1,6 For square neck bolts, the hole shall be adapted to admit the square neck. Table 11 -- Wedge dimensions iominal diameter >f bolt and screw d Property classes fo~ bolts with plain shank length /~>2d 3.6,4 .6,4.8,5.6 5.8,8.8,9.8, mm d~20 2016 mm can be tested, 8.8 Head soundness test for full-size bolts and screws with d <10 mm and with lengths too short to permit wedge load testing The head soundness test shall be carried out as illustrated in figure 4. 17 IS 1367 (Part 3):2002 ISO 898-1 :1999 When struck several blows with a hammer, the head of the bolt or screw shall bend to an angle of 900-/3 without showing any sign of cracking at the shank head fillet, when viewed at a magnification of not less than X 8 nor more than x 10. Where screws are threaded up to the head, the requirements in the first thread, provided that the head does not snap off. may be considered met even if a crack should appear h -9 NOTE 1 NOTE 2 For dh and r2 (r2 = r,), see table 10. The thickness of the test plate should be greater than 2 d. Figure 4 -- Head soundness test Table 12 -- Values of angle ~ Property class P 3.6 4.6 60° 5.6 4.8 5.8 6.8 8.8 80° 9.8 10.9 12.9 8.9 Decarburization test: evaluation of surface carbon condition Using the appropriate measuring method (8.9.2.1 or 8.9.2.2 as applicable), a longitudinal section of the thread shall be examined to determine whether the height of the zone of base metal (E) and the depth of the zone with complete decarburization (G), if any, are within specified limits (see figure 5). The maximum value for G and the formulae for the minimum value for E are specified in table 3. 18 IS 1367 (Part 3) :2002 ISO 898-1 :1999 1 Key 1 2 3 4 HI Completely decarburized Partially decarburized Pitch line Base metal is the external thread height in the maximum material condition. Figure 5 -- Zones of decarburization 8.9.1 Definitions 8.9.1.1 base metal hardness hardness closest to the surface (when traversing from core to outside diameter) just before an increase or decrease occurs denoting carburization or decarburization respectively 8.9.1.2 decarburization generally, loss of carbon at the surface of commercial ferrous materials (steels) 8.9.1.3 partial decarburization decarburization with loss of carbon sufficient to cause a lighter shade of tempered martensite and significantly lower hardness than that of the adjacent base metal without, however, showing ferrite grains under metallographic examination 8.9.1.4 complete decarburization decarburization with sufficient examination 8.9.1.5 carburization result of increasing 8.9.2 8.9.2.1 Measurement Microscopic carbon loss to show only clearly defined ferrite grains under metallographic surface carbon to a content above that of the base metal methods method of E and G. This method allows the determination 19 IS ISO 1367 898-1 [Part 3) :2002 :1999 The specimens to be used are longitudinal sections taken through the thread axis approximately half a nominal diameter (% d) from the end of the bolt, screw or stud, after all heat-treatment operations have been performed on the product. The specimen shall be mounted for grinding and polishing in a clamp or, preferably, a plastic mount. After mounting, grind and polish the surface in accordance with good metallographic in ethanol) is usually practice. suitable to show changes in Etching in a 3 % nital solution (concentrated microstructure caused by decarburization. Unless otherwise nitric acid agreed between the interested patties, a x 100 magnification shall be used for examination. If the microscope is of a type with a ground glass screen, the extent of decarburization can be measured directly with a scale. If an eyepiece is used for measurement, it should be of an appropriate type, containing a cross-hair or a scale. 8.9.2.2 Hardness method (Referee method for partial decarburization) method is applicable only for threads with pitches, P z 1,25 mm. are made at the three points shown on figure 6. Values for E are given in The hardness measurement The Vickers hardness measurements table 13. The load shall be 300 g. The hardness determination for point 3 shall be made on the pitch line of the thread adjacent to the thread on which determinations at points 1 and 2 are made. The Vickers hardness value at point 2 (HV.J shall be equal to or greater than that at point 1 (HV1) minus 30 Vickers units. In this case the height of the non-decarburized zone E shall be at least as specified in table 13. The Vickers units. Complete method. hardness value at point 3 (HVJ shall be equal to or less than that at point 1 (HV1 ) plus 30 Vickers decarburization up to the maximum specified in table 3 cannot be detected by the hardness measurement Dimensions in millimetres 2 4 I 0,14 1 3 Key 1,2, 3 Measurement points 4 Pitch line Figure 6 -- Hardness measurement for decarburization test 20 IS 1367 ISO 898-1 (Part 3) :2002 :1999 Table 13 -- Values for HI and E Pitch of the thread F mm HI mm 8.8, 9.8 Property class 10.9 12.9 0,5 0,6 0,7 0,8 1 0,613 0,307 0,409 0,460 1,25 0,767 0,384 0,511 0,575 1,5 0,920 0,460 0,613 0,690 1,75 1,074 0,537 0,716 0,806 2 1,227 0,614 0,818 0,920 2,5 1,534 0,767 1,023 1,151 3 3,5 4 2,454 1,227 1,636 1,841 0,307 0,368 0,429 0,491 0,154 0,184 0,215 0,245 1,840 2,147 0,920 1,227 1,380 1,074 1,431 1,610 Emlnb mm 0,205 0,245 0,286 0,327 0,230 0,276 0,322 0,368 I a For p s I mm, rnicroscopiC metlmclOnlY. I b Calculated on the basis of the specification in 5.16, see table 3. 8.10 Retempering test The mean of three core hardness readings on a bolt or screw, tested before and after retempering, shall not differ by more than 20 HV when retempered at a part temperature 10 `C less than the specified minimum tempering temperature and held for 30 min. 8.11 Surface discontinuity inspection inspection, see ISO 6157-1 or ISO 6157-3 as appropriate. inspection is applied to test bolts before machining. For the surface discontinuity In the case of test programme A the surface discontinuity 9 Marking Mechanical accordance fasteners manufactured to the with the provisions of 9.1 to 9.5. requirements of this International Standard shall be marked in Only if all requirements in this part of ISO 898 are met, shall parts be marked and/or described designation system described in clause 3. Unless otherwise specified in the product standard, the height of embossed not be included in the head height dimensions. Marking of slotted and cross recessed screws is not usual. markings according to the on the top of the head shall 9.1 Manufacturer's identification marking A manufacturer's identification mark shall be included during the manufacturing process, on all products which are marked with property classes. Manufacturer's identification marking is also recommended on products which are not marked with property class. For the purposes of this part of ISO 898 a distributor considered a manufacturer. marking fasteners with his unique identification mark shall be 9.2 Marking symbols for property class Marking symbols are shown in table 14. 21 IS 1367 (Part 3) :2002 ISO 898-1 :1999 Table 14 -- Marking symbols Property class Marking symbol "b 3.6 3.6 4.6 4.6 4.8 4.8 5.6 5.6 5.8 5.8 6.8 6.8 8.8 8.8 9.8 9.8 10.9 10.9 m -lo9b 12.9 12.9 a The full-stop in the marking symbol maybe omitted. b When low ~a~on ma~ensitic steels are used for propefly class 10.9 (see table 2 ). In the case of small screws or when the shape of the head does not allow the marking as given in table 14 the clock face marking symbols as given in table 15 may be used. Table 15 -- Clock-face system for marking bolts and screws Property class I ,6 Q ,0 ~ ,0 Marking symbols b b Property class ,6 ,6. ,6 ;6 ;6 a6b b a The twelve o'clock posltlon (reference mark) shall be marked either by the manufacturer's Identlficatlon mark or by a b POlnt. The property class IS marked by a dash or a double dash and m the case of 12.9 by a point 9.3 Identification 9.3.1 Hexagon and hexalobular head bolts and screws with the Hexagon and hexalobular head bolts and screws (including products with flange) shall be marked manufacturer's identification mark and with the marking symbol of the property class given in table 14. The marking is obligatory for all property classes, preferably on the top of the head by indenting or embossing or on the side of the head by indenting (see figure 7). In the case of bolts or screws with flange, marking shall be on the flange where the manufacturing process does not allow marking on the top of the head. Marking is required for hexagon and hexalobular head bolts and screws with nominal diameters d z 5 mm. 22 IS ISO 1367 898-1 (Part 3) :2002 : 1999 @@ a b Manufacturer's identification mark Property class Figure 7 -- Examples of marking on hexagon and hexalobular head bolts and screws 9.3.2 Hexagon and hexalobular socket head cap screws identification mark and Hexagon and hexalobular socket head cap screws shall be marked with the manufacturer's with the marking symbol of the property class given in table 14. The marking is obligatory for property classes 8.8 and higher, preferably on the side of the head by indenting or on the top of the head by indenting or embossing (see figure 8). Marking is required for hexagon and hexalobular socket head cap screws with nominal diameters d >5 mm. Figure 8 -- Examples of marking on hexagon socket head cap screws 9.3.3 Cup head square neck bolts with the manufacturer's Cup head square neck bolts with property classes 8.8 and higher shall be marked identification mark and with the marking symbol of the property class as given in table 14. The marking is mandatory embossing (see Figure 9). for bolts with nominal diameters d >5 mm. It shall be on the head by indenting or Y . . 8.8 @ . Figure 9 -- Example of marking cup head square neck bolts 23 IS ISO 1367 898-1 (Part 3) :2002 :1999 9.3.4 Studs Studs with nominal thread diameters d >5 mm, of property class 5.6 and property classes 8.8 and higher shall be marked by indenting with the marking symbol of the property class as given in table 14 and the manufacturer's identification mark on the unthreaded part of the stud (see Figure 10). If marking on the unthreaded part is not possible, marking of property class only on the nut end of the stud is allowed, see figure 10. For studs with interference fit, the marking shall be at the nut end with manufacturer's identification marking only if it is possible. I i 5.6 XYZ K k I Figure 10 -- Marking of studs The symbols in table 16 are permissible as an alternative Table 16 -- Alternative Property class Marking symbol 9.3.5 5.6 identification of property classes. marking symbols for studs 8.8 9.8 10.9 12.9 0 + c1 A * in the previous paragraphs of Other types of bolts and screws If agreed between the interested parties, the same marking systems as described clause 9 shall be used for other types of bolts and screws and for special products. 9.4 Marking of bolts and screws with left-hand thread Bolts and screws with a left-hand thread shall be marked with the symbol shown in figure 11, either on the top of the head or on the point. Marking is required for bolts and screws with nominal thread diameters d >5 mm. Figure 11 -- Left-hand thread marking 24 IS 1S0 1367 898-1 (Part 3) :2002 :1999 Alternative marking for left-hand thread as shown in figure 12 may be used for hexagon bolts and screws. .--. * P A k/2 u k Key s is the width across flats h' is the height of the head Figure 12 -- Alternative left-hand thread marking 9.5 Alternative marking Alternative or optional permitted marking as stated in 9.2 to 9.4 should be left to the choice of the manufacturer. 9.6 Marking of packages identification and property class is mandatory on all packages for all sizes. Marking with manufacturer's 25 IS ISO 1367 898-1 (Part 3) :2002 :1999 Annex A (informative) Lower yield stress or stress at 0,2 YO non-proportional elevated temperature elongation at The mechanical properties of bolts, screws and studs will vary in a variety of ways with increasing temperature. Table A.1, which is for guidance only, is an approximate representation of the reduction in lower yield stress or 0,2 % non-proportional elongation which may be experienced at a variety, of elevated temperatures. These data shall not be used as a test requirement. Table A.1 -- Lower yield stress or stress at 0,2 % non-proportional Temperature + 20 Property class +100 + 200 Lower yield stress, ReL or stress at 0,2% non-proportional elongation RP0,2 N/mm2 5.6 8.8 10.9 m 12.9 300 640 940 940 1100 270 590 875 -- 1020 230 540 790 -- 925 215 510 745 -- 875 195 480 705 -- 825 elongation "C + 250 + 300 at elevated temperature Continuous operating at elevated service temperature may result in significant stress relaxation. Typically 100 h service at 300 "C will result in a permanent reduction in excess of 25 ?4. of the initial clamping load in the bolt due to decrease in yield stress. 26 Bureau of Indian Standards BIS is a statutory institution established under th~llureau oflndian Standards Act, 1986 to promote harmonious development of the activities of standardization, marking and quality certification of goods and attending to connected matters in the country. Copyright BU3has the copyright of all its publications. No part ofthese publications maybe reproduced in any form without the prior permission in writing of BIS. This does not preclude the free use, in the course of implementing the standard, of necessary details, such as symbols and sizes, type or grade designations. Enquiries relating to copyright be addressed to the Director (Publications), BIS. Review of Indian Standards Amendments are issued to standards as the need arises on the basisof comments. 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